I don't think there is a line, with my gf, if there is she pushes it further each time.

What's your opinion on when tickling goes into an area that's really not condonable?
One example for me would be tickling in public were it might be embarrassing for the Lee.
If someones safeword is ignored and the tickler purposely doesn't stop then thats going too far. Some do like being pushed past limits so it's something that should be mentioned before the tickling starts.
To me, it crosses the line when it is non-consensual, and when it is viewed by third parties who don't wish to see it.
When does tickling cross the line?